1. Field of the Invention
The present invention relates to an image forming apparatus supervising system connecting an image forming apparatus and a host machine via a communication line and, more particularly, to a communication control device connected between the image forming apparatus and the communication line for controlling their communication.
2. Discussion of the Background
An image forming apparatus supervising system of the type described may connect a plurality of copiers or similar image forming apparatuses to a host machine located at, for example, a remote service center over a switched telephone network or similar communication line. This kind of system is disclosed in Japanese Patent Laid-Open Publication (Kokai) Nos. 257155/1990, 259666/1990, and 196053/1991 by way of example. In such a system, a single host machine controls a plurality of remote image forming apparatuses collectively so as to add up the conditions of the individual apparatuses relating to use and to effect maintenance. The conditions relating to use include the number of copies produced. Regarding maintenance, each image forming apparatus may call the host machine automatically after self-diagnosis, or the host machine may access the individual apparatuses to adjust various portions thereof. Today, it is a common practice with this kind of system to read a counter (generally the number of copies produced) built in each image forming apparatus by remote control, thereby charging the user of the apparatus for a maintenance contract.
However, the problem with the conventional supervising system is that even when the image forming apparatus and the host machine are connected by a communication line, the host machine cannot read the above-mentioned particular data out of the apparatus if the power supply to the apparatus is shut off. As a result, the time when the host machine can read the data is limited. For example, although the host machine should preferably read the data out of the image forming apparatus at nighttime during which communication cost is low and traffic is light, i.e., a high connection rate is achievable, the power supply to the apparatus is often shut off at nighttime.